1. Field of the Invention
The present invention relates to a silver halide photographic light-sensitive material, and particularly to a silver halide photographic light-sensitive material exhibiting high sensitivity, reduced fogging, and in addition, with reduced variation in sensitivity when time passes from exposure to development.
2. Description of the Related Art
There are various silver halide photographic light-sensitive materials currently available from the market and methods of forming images thereon. They are used in wide fields. In recent years, there are stronger needs for enhancing a quick processing performance of color printing papers, and thus many studies have been conducted. It has already been known that when the silver chloride content in silver halide emulsion to be used is increased, developing speed is dramatically enhanced. In the market, emulsions used for color printing papers have come to contain richer silver chloride.
Moreover, in response to diversified needs of users, a variety of print sizes with greater magnifications such as a panorama size, a high-vision size, etc. have come to be easily obtained. In order not to impair productivity in cases where such prints with greater magnifications are exposed, techniques for improving sensitivity of light-sensitive materials are still more desired. However, in the manufacture of silver halide emulsions with a high silver chloride content, there is a drawback that ordinary chemical sensitization hardly permits production of emulsions with high sensitivity. Accordingly, in silver chloride-rich emulsions, attempts have been made to enhance their sensitivities.
Among the attempts, it has conventionally been known that incorporation of silver halide emulsion which has undergone chemical sensitization with a gold, selenium, or tellurium compound into a light-sensitive material is effective for achieving high sensitivity. (See, for example, U.S. Pat. No. 2,642,361, JP-B-43-13,489, and Canada Patent No. 800,958.) However, light-sensitive materials containing silver halide emulsions which have been chemically sensitized sometimes cause considerable fogging despite their improved sensitivity. Therefore, it is necessary that some measure must be taken to reduce fogging.
For example, azaindenes, azoles, heterocyclic mercapto compounds and thioketo compounds are known as antifoggants. Particularly, it is known that mercapto compounds such as metcaptothizoles, mercaptobenzothiazoles, mercaptobenzimidazoles, mercaptothiadiazoles, mercaptotetrazoles, and mercaptopyrimidines are effective.
U.S. Pat. No. 3,047,393 and JP-B-58-27,486 disclose the use of thiosulfonic compounds as antifoggants.
In addition, U.S. Pat. No. 2,394,198 and WO No. 92-12,462 disclose a method of preventing fogging by combined use of a thiosulfonic compound and a sulfinic compound.
The present inventors used the above techniques to investigate both high sensitization and reduction in fogging of red-sensitive emulsions by gold, selenium and tellurium. As a result, it was confirmed that there was obtained an effect of reducing fogging when the above-mentioned mercapto compounds or thiosulfonic compound was used. However, the effect was not at a sufficient level.
On the other hand, when a thiosulfonic compound and a sulfinic compound were used in combination, fogging was remarkably reduced. In these attempts, there occurs a drawback that considerable variation in sensitivity is caused when time passes from exposure to development.